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remaining cases the onset and/or aggravation of cardiocirculatory problems made it
impossible to perform the test. This observation caused us to follow up our findings
with these patients using only sonographic tests until its resolution, and this was
confirmed by an evaluation using MSCT which showed a perfect overlap between
the two imaging techniques. This was the case in 8 of the 13 patients monitored; in
the remaining 5, due to the persistence of ischemic regions and associated paren-
chymal retraction, follow-up was done using CEUS alone (Fig. 2.1).
Fig. 2.1 Baseline exam that appears negative; late CEUS image in the late phase shows a
triangular avascular area with a cortical base with ischemic traits (a, b). c The cortico-medullary
phase of the MSCT scan highlights a finding that fully matches that of the CEUS exam
6 2 The Kidney
2.2 Traumatic Pathology
In order to speak about trauma, it becomes necessary to define the term. In the
most severe cases of trauma, CEUS would not be the first choice among proce-
dures: this type of patient must be evaluated using MSCT, a technique with the
advantages of a high spatial and temporal resolution, coverage of wide corporal
bodies, the narrowness of the slice, quick execution time and the possibility to
build 2D and 3D reconstructions [6, 7].
Contrast-enhances ultrasound is recommended in minor traumas or more severe
traumas in stable patients, or to follow up on renal lesions which appear on the
MSCT scan. Both from the review of literature [6, 8] and on the basis of our case
studies, we find CEUS is a quick and simple means to identify various types of renal
lesions: lacerations appear as avascular regions with fairly ragged borders which
extends in an irregular way across the healthy parenchyma (Fig. 2.2); in severe
cases it is impossible to recognize the normal renal appearance. The peri- and
parirenal hematoma is visible, with possible signs of active bleeding, often asso-
ciated with lacerations, indicated by a blush of contract medium, which can be seen
in the early phase of the exam (Fig. 2.3). The vascular renal hilum lesion is char-
acterized by a complete lack of post-ultrasound saturation of the parenchyma. This
occurrence, like renal lesions of a high degree, are difficult to notice using CEUS,
inasmuch as they usually are found in poly-traumatized and or unstable patients [7].
Fig. 2.1 (continued)
2.2 Traumatic Pathology 7
In our experience over the course of 2 years, we have evaluated 255 stable patients
with minor closed trauma, with and without hematuria; and using CEUS we have
identified 28 lesions confirmed by MSCT, and by comparison of the images dis-
tinguished three levels of damage: minor (corresponds more or less with grade 1 of
the American Association for the Surgery of Trauma—AAST), medium (corre-
sponds with grades 2 and 3 of AAST classification) and high (corresponds with
grade 3 and 4 of AAST classification) [7]. Experience has also shown that in cases
of minor trauma, with ribs lesions, of ‘‘parasurgical’’ operations on the kidney
Fig. 2.2 a Laceration of the upper pole of the right kidney: CEUS shows a thin linear avascular
area with perirenal hematoma. b MSCT scan, after intravenous infusion of contrast agent,
displays the same as (a), with substantially similar results
8 2 The Kidney
(lithotripsy, biopsy, nephrostomy, etc.) with hematuria, rapid and progressive
anemia, the baseline ultrasound should always be supplemented by a CEUS eval-
uation. The main limit of the method is found in the lack of a means to evaluate the
integrity of the urinary tract in relationship with the lack of excretion with that
means of CM. Another application is for follow-up: considering the diagnostic
overlapping of CEUS with MSTC, it is mandatory, on the bases both of our case
studies as well as current literature [1, 6–8], to carry out the monitoring of the
evolution of traumatic renal lesions using CEUS, in order to achieve the following
goals: to avoid use of radiation for patients (often young ones), to avoid the use of
nephrotoxic agents, more adequate diagnostic accuracy and cost savings.
Fig. 2.3 a Static image, extrapolated by dynamic recording in video clips, displays both
extensive pararenal bruising (star), and an active exstavasation (blush) of the ultrasound contrast
agent (arrow) indicating a lesion of the renal cortical vessels after lithotripsy. b MSCT scan
(multi-planar reconstruction) of the case of ( a) which identifies the same highlighted findings of
the CEUS exam: pararenal hematoma (star) and blush (arrow)
2.2 Traumatic Pathology 9
2.3 Transplantation
CEUS is a non-invasive method which is useful in the identification of vascular
and non-vascular complications in kidney transplant [1, 3, 5, 9]. Post-transplant
complications can be early or late. Early complications arrive in the first week after
Fig. 2.4 Perirenal fluid collection: the baseline (a) does not permit the definition of the
extension and nature. The CEUS image (b–c) identifies not only the extension and the
homogeneously non-echogenic and non-corpuscular nature of the collection, compatible with
seroma, but also shows the conditions of the parenchyma
10 2 The Kidney
the transplant and include: acute rejection, tubular necrosis, hematoma, pyelone-
phritis, abscess, urinoma, ureteral obstructions, or vascular obstructions [10, 11].
Late complications appear beginning several weeks after the transplant and
include: chronic rejection, ureteral obstructions, cysts, cancer, and complications
related to immunosuppressive therapies, such as for lymphoma and cancer, and
infections particularly risky in kidney transfer [10–13]. In adults, the transplanted
kidney is placed in the heterotopic extraperitoneale space in the iliac fossa with
end-to-side anastomosis between the renal artery and the external or common iliac
artery. The vesicoureteral anastomosis is usually done close to the trigone, with the
creation of a submucous tunnel that prevents reflux.
2.3.1 Perirenal and Renal Fluid Collections
These are frequent and include hematoma, (late) lymphocele, (early) seroma,
abscess, and urinoma. In CEUS these collections appear with no enhancement:
using this procedure it is possible to define them and establish the anatomic
relationships with adjacent structures (Fig. 2.4a–c). Additionally, the method can
be of help in cases of puncture and drainage.
Fig. 2.4 (continued)
2.3 Transplantation 11
2.3.2 Vascular Complications
Renal and iliac artery stenosis
The first is usually found in the perianastomotic zone, is the most common vas-
cular complication and can be found at both early and late stages. Stenotic
Fig. 2.5 a Transplanted kidney with stenosis of the arterial iliac-renal anastomosis: the CEUS
shows a widespread reduction in parenchymal perfusion. b MSCT (coronal reconstruction)
confirms the presence of an area of reduced saturation after the infusion of contrast medium
12 2 The Kidney
complications are due to the onset of arterial hypertension after the transplant. In
the case of hemodynamically significant stenosis, CEUS shows perfusion defects
in the renal parenchyma that can affect the entire parenchyma (Fig. 2.5) or only
select regions, most often peripheral ones, such as the polar regions bordering
both ischemic regions and hypoperfused neighboring zones (Fig. 2.6). [1, 9, 11, 14]
Fig. 2.6 a–d Sectoral lack of vascularization in the lower polar region of the transplanted
kidney, evaluated with the Power-Doppler (a). Multi-phase CEUS confirms the area with no
perfusion indicative of hypoperfusion, which appears to be extended beyond (b–c)
2.3 Transplantation 13
Renal artery thrombosis
Thrombosis of the renal artery is a vascular complication with immediate systemic
or surgical causes. It causes renal infarctions due to lack of parenchymal
enhancement and capsular enhancement [1, 10, 15].
Intrarenal pseudoaneurysms and arteriovenous fistulas
These are iatrogenic complications that follow a percutaneous biopsy. The first are
subsequent to an arteriovenous laceration, the second after an exclusively arterial
lesion [11–13]. In our experience, we found that the presence of a stenosis of the
Fig. 2.6 (continued)
14 2 The Kidney
renal artery, anastomosed with the iliac artery, was linked to the presence of an
arteriovenous fistula that developed after a biopsy to assess a rejection, which in
the case study was indicated by the absence of perfusion (Fig. 2.7).
Fig. 2.7 a–f Integrated CEUS and MSCT imaging of renal artery stenosis anastomosed with the
external iliac artery (arrow) and (e) and a post-biopsy fistula in an acute rejection with
simultaneous opacity of the artery (f)(gray arrow) and renal vein (red arrow). The more
panoramic view of MSCT allows for a diagnosis; CEUS identified the absence of parenchymal
perfusion and heavy saturation of the two vascular compartments (a–c)
2.3 Transplantation 15